The reader is introduced to the book through a concise comparison of Proclus’ philosophical-theological system with that of the Chaldean Oracles. After briefly describing the impasse current research is facing in trying to reconstruct the nature of the Chaldean First Principle, that is, whether it must be conceived of as a monad or identified with Numenius’ First Intellect, the reader is shown how a reassessment of Proclus’ interpretation of the Oracles could help to overcome this as well as other hermeneutical problems in the historicocritical reconstruction of Chaldean doctrine. The main goal that the book intends to achieve is to show how Proclus’ interpretation of the Oracles is generally in line with their original meaning (to the extent that this is independently identifiable and comparable with Proclus’ exegesis of it) and usable by modern research to deepen its knowledge of the Chaldean Oracles.